1. Technical Field
The invention relates generally to an improved suspension system for land vehicles. More particularly, the invention relates to trailing or leading beam air suspension systems. Specifically, the invention relates to trailing or leading beam air suspension systems having one air bladder per axle longitudinally aligned with its respective axle and being fastened to the vehicle frame and its respective axle or connecting beam.
2. Background Information
With the advent following World War II of large load carrying capacity trucks and trailers in this country, came the need to provide vehicles with multiple axles for increasing the capacity of trucks over that of previously existing designs. These large loads could not be carried by the then existing technology generally comprising one rear axle supporting the majority of the load on the trailer.
While the use of additional axles effectively increased load-carrying capacity, it was soon realized that as the number of load bearing axles increased on a given vehicle, a number of difficulties arose. Specifically, tire scuffing, loss in fuel economy, and the inability to safely corner, all were problems associated with multiple axle vehicles. These problems were in addition to the standard problems associated with load bearing axles such as the providing of sufficient strength to resist lateral and axial deflection. In the case of one or multiple axles, many factors account for the various current and past suspension designs as the mitigation of these problems was a primary concern to the industry resulting in the development of a variety of suspension systems, both liftable and non-liftable.
Liftable suspensions could be selectively raised from the road surface or lowered into engagement with the road surface when needed, thereby mitigating a number of the aforementioned problems. However, these liftable suspensions added significant weight to the suspension system, and required additional parts such as lifting apparatus which complicated the suspension system, all of which lowered load carrying capacity and increased the complexity and costs of servicing the system.
Alternativley, non-liftable axles have been designed for a variety of purposes as many vehicles continuously or almost continuously require additional load-carrying capacity and thus require auxiliary suspension system. Examples of such vehicles requiring auxiliary suspensions include trash compactor trucks, concrete mixing and delivery vehicles. These trucks require additional suspensions as the truck has a relatively large weight when compared to the overall vehicle length.
As is well known in the art, suspension systems may take a variety of forms, including parallelogram suspensions, and leading and trailing beam-type suspensions. All of these systems have become complicated and heavy to account for or attempt to account for a variety of problems such as those indicated above. The need thus exists for a suspension system which is simple, lightweight, safe, and provides adequate vertical load-carrying characteristics. Additionally, the need exists for a suspension system which provides an axle to beam connection which is lightweight, easy to assemble, and simple to manufacture.
As trucks continue to carry additional weight, it is necessary to provide a method of supporting the vertical load associated with the trailer without unduly increasing the weight and cost associated with the suspension system. In the past, such vertical load has been taken up with the use of air springs positioned between the leading or trailing beam, or parallelogram suspension system and the vehicle frame. While the use of air springs is presumably adequate for the purpose for which it is intended, the use of such air springs create a number of drawbacks. Most notably, such air springs are relatively expensive, and as the vehicle is required to carry more load, the size of the air spring must correspondingly increase. Additionally, the air spring operates through a relatively small area such that the force of the air spring over any given square unit is relatively large. Lastly, these air springs, due to the relatively high force acting on the spring itself, must be mounted with complicated mounting means such as bolts and pins.
The need thus exists for an air suspension which will allow the air spring to operate over a much larger area thereby significantly reducing maximum loads on the air spring, and which, as a result of the reduced force on the air spring, may be attached by more convenient methods.
Objectives of the invention include providing a vehicle suspension system which is of a more simplistic construction, lightweight, more cost effective to manufacture, easy to assemble and maintain, and simple to manufacture.
Another objective is to provide a suspension system which provides an improved ride.
Still another objective is to provide a suspension system which provides adequate vertical load carrying characteristics with an improved, cost effective, and simple design.
Yet another objective is to provide an improved air spring for use with a suspension system where the air spring is simplistically and economically attached to both the vehicle frame and the axle or beam.
Still another objective is to provide a vehicle suspension system where the vertical load acting on the air spring is significantly reduced.
Yet another objective is to provide an improved suspension system where the maximum vertical load acting on the air spring is significantly reduced.
An even further objective is to provide a vehicle suspension system which utilizes an air spring which operates over a significant larger area than heretofore possible.
Still an even further objective is to provide a vehicle suspension system which may be utilized as both a liftable and non-liftable suspension system.
Still one more objective is to provide a vehicle suspension system which will operate equally well on most vehicles.
An additional objective is to provide such a vehicle suspension system which is of simple construction, which achieves the stated objectives in a simple, effective and inexpensive manner, and which solves problems and satisfies needs existing in the art.
These and other objectives and advantages of the invention are obtained by the improved suspension system adapted to be mounted to a vehicle, the general nature of which may be stated as including a suspension frame attached to the vehicle frame, an axle of a first length, a pair of hanger brackets adapted for extending from the suspension frame and for supporting the suspension system, a central beam pivotally attached to the hanger brackets and extending therefrom to the axle, the central beam having a first width substantially the same as the first length, a support plate securely affixed to the suspension frame, an air spring of substantially the first length and adapted to be positioned intermediate the central beam and the vehicle frame, and a plurality of fasteners affixing the air spring to the support plate.